It is known to design the filler connection for a fuel tank in one piece with the filling tube; length and guidance of the filling pipe which normally consists of sheet metal being governed in this arrangement by the position of the fuel tank. Even though the construction of the one-piece filling tube does not cause so much difficulties problems, however, will arise in connection with the fitting thereof in the body. As there is no elastic intermediate member available, it is difficult to match the tolerances of tank and body. For the above reason the filler connections are normally manufactured as separate parts which are then soldered, welded or otherwise connected, for instance, through an elastic socket or with the aid of pipe clips or the like. But even these filler connections suffer from quite a few drawbacks. Because of the metallic material numerous reworking operations are necessary which brings about corresponding expenses in terms of manufacturing costs. Numerous additional elements are required for fastening to and sealing with respect to the body. Usually, the known filler connections are fastened at the body by means of several screws tightly pulling the filler connection against the sheet metal of the body.
To prevent corrosion the filler connections are covered with a corrosion protection means the layer of which may be easily damaged in the rough operation during the filling-in of the fuel so that corrosion will yet occur. What is furthermore disadvantageous is that it is difficult with a pipe construction of sheet metal to arrive at small structural dimensions because the overflow connection, in particular, must be designed in the form of a pipe bend and thus requires considerable space.
The "tank cover" which closes the filler connection outside is either designed in the manner of a bayonet closure (which is the most widely accepted embodiment) or is provided with an inner or outer thread and screwed onto the connection. With both types of closure, however, difficulties will result as regards the loosening moment. With a bayonet closure the possible forces of stripping off the cover are relatively small and, in addition, are strongly dependent upon the properties and the design of the material that has been selected. With a threaded closure the loosening moment of the cover is strongly dependent upon the tightening moment, especially because of an axial sealing being used. For this reason, many threaded covers are provided with a special ratchet arrangement. Furthermore, it is difficult with a filler connection of sheet material to provide a greater threaded engagement for the closure lid so that here as well the pull-off forces are relatively low.
Additional provisions are required at the overall tank system to guarantee operation and safety in a satisfactory manner. This includes valve means for ventilation during fuel consumption and venting in case overpressure should occur, for instance, due to heating in the sun, etc. Furthermore, care must be taken for the air present in the tank to escape quickly enough during the filling-in of the liquid fuel. In many cases the valve means are provided in the closure lid which, consequently, is of an extremely expensive design. Another disadvantage of the closure lid performing valve functions resides in that fuel escaping through the venting valve will form traces over the outside of the body thus causing an increased danger of fire.
The invention has for its object to provide a filler connection for vehicles equipped with internal combustion engines which avoids the above mentioned disadvantages, is of a simple design and may be easily fitted, while being provided with a simply equipped closure lid through which no fuel may escape to the outside of the vehicle.
With a filling connection of the type mentioned at the beginning this problem is solved in that it is formed integrally of synthetic material and the valve means are arranged on the portion disposed on the inside of the body.
The filler connection according to the invention is a member of synthetic material formed in one piece which may be designed in such a manner that it is in a position to perform all the necessary functions satisfactorily. This includes the arrangement of the valve means at the filler connection so that the closure lid may correspondingly be manufactured as a member of a simple construction which is formed in one piece - in an embodiment not adapted to be closed. For this reason, the fuel is unable to escape outside and cannot mar the good appearance of the outer skin of the body and cause an increased danger of fire.
Through the formation of the filler connection in accordance with the invention as a member of synthetic material it is possible to obtain a favourable configuration also with a view to the fastening in a sheet metal member of the outer skin of the vehicle. In this connection provision is made in one embodiment of the invention for the filler connection to be in snapping engagement in the body opening and fastened therein. Therefore, there are no additional parts necessary to fasten the filler connection, and also the mounting itself is extremely simple because the filler connection has only to be introduced and snapped into the sheet metal opening. In this connection provision is made in another embodiment of the invention for the use of elastic synthetic material and for a radial abutment, preferably a flange formed integrally therewith, said flange lying close to one side of the body skin while at least one arresting nose is formed integrally on the other side of the body skin. If, in accordance with another embodiment of the invention, an annular seal is arranged between the abutment and the body skin, there will result not only an extremely simple and secure fastening but also a sufficient sealing of the connection in the opening, so that for instance when filling-in fuel no liquid whatsoever can flow past the filler connection and into the interior of the body.
The filler connection in accordance with the invention furthermore possesses the advantage that it may be equipped with a sufficiently strong and long thread which will permit fastening of the closure lid by threaded engagement. In this connection, provision is made in another embodiment of the invention for the outer portion to have a external thread formation, preferably a sawtooth thread formation onto which the lid can be screwed by means of a fitting inner thread, said lid being likewise preferably formed in one piece from synthetic material. With the aid of such a closure it is rendered possible for the loosening moment of the closure lid to be made approximately as great as the tightening moment, especially, if, in accordance with another embodiment of the invention, there is an axially and/or radially effective annular seal arranged at the thread of the lid, with the seal disposed at the inner surface of the thread of the lid and cooperating with the end face of the outer portion of the filler connection or arranged at the lower end of the thread of the filler connection and cooperating with the inside of the outer portion of the lid. The sealing element is preferably endowed with a relatively high elasticity of its own or dimensional elasticity, respectively, and is resistant to fuel.
To avoid an inadmissibly high torque and extremely high loads on the sealing caused thereby, provision is made in another embodiment of the invention for the lid to have a limiting abutment preferably in the form of a rib on the inside thereof, said abutment cooperating with a limiting abutment on the inside of the filler connection likewise shaped preferably in the form of a rib formed integrally therewith. In this arrangement, the inwardly disposed abutment rib may additionally be made use of as an undercut for the closing pin of a lock which may perhaps be provided in the lid. The volume of the filler connection in accordance with the invention disposed on either side of the sheet metal of the body preferably extends approximately horizontally with a downwardly bent pipe connection adjoining said region on the inside which is connected with the filling tube or hose to the tank. In accordance with another embodiment of the invention the pipe connection is provided with a radial projection in the region of the bend, preferably in the form of a flange. The radial projection limits the passage cross sectional area of the filler connection for tank guns. It is possible to vary the passage cross sectional area selectively by simply replacing the mold core in the production of the filler connection according to the invention, in order to thus adapt the passage cross sectional area to different tank guns.
Provision is made in another embodiment of the invention for the inner portion to have two parallel discharge connections integrally formed thereat, coaxially with the axis of the outer portion. The one discharge connection is connected with the fuel tank through a line or pipe in order to vent the latter when fuel is filled in. Any fuel entrained in this venting operation is subsequently returned into the filler connection and thus into the tank, immediately. The other discharge connection is connected with the venting valve through which in case of overpressure fuel vapours and thus also fuel entrained therewith, are discharged. A suitable conduit is connected to this discharge connection leading the exiting medium to the bottom of the vehicle.
Owing to the arrangement of the discharge connections as selected and, in addition, due to the bending-off of the farthest inwardly disposed part of the pipe connection it is possible with the invention to mount the connection from the outside of the body. As already explained above, the fastening is suitably effected by means of a snapping connection. With extremely thin sheet metal members it will perhaps become necessary to provide a clamping plate to accommodate the surface pressure from inside.
With the filler connection in accordance with the invention the valve means are associated to the filler connection proper, so that the closure lid may be of a simple construction and configuration. It is furthermore possible to use only one basic housing member both for the closable and the non-closable version. The parts of the lock are preferably mounted in the center portion of the lid, in recesses already provided for this purpose. In the process of production only one mold core has to be replaced in order to make possible the break-through for the lock. As regards the valves provision is made in one embodiment of the invention for two valves to be arranged preferably side by side in the upper region of the inner portion. In this connection, provision is made in another embodiment of the invention for the discharge connection for tank venting during filling to be disposed below the valves but above the pipe connection. It is particularly advantageous if the valves in accordance with the invention comprise two housing portions one of them formed integrally with the inner portion of the filler connection. The discharge connection for the overpressure valve in this arrangement is then suitably arranged at the other housing member.
If possible, the valves will be designed in such a manner that they are formed as far as possible in the formation of the connection proper. In this connection provision is made in another embodiment of the invention for the valves to be membrane valves having a membrane element provided with an opening and a valve seat element movable in limits, preferably a ball, which may be sealingly engaged with the opening. Such a valve makes use of the favourable properties of responsiveness of a membrane valve but avoids the disadvantage of too rapid wear and contamination by the provision of a valve seat element supported for limited movement which is adapted to be brought into sealing engagement with the sealing opening in the membrane element. The movability of the valve seat due to the movable valve seat element ensures a constant cleaning of the valve seat so that even with a contaminated medium the functional safety of the valve is not impaired. A support of the valve seat element for limited movement in addition offers the advantage that a displacement of the sealing opening from the center due to manufacturing tolerances or later influences may be accommodated and cannot have any disadvantageous effects on the sealing properties. The valve housing preferably consists of two members adapted to be connected with each other, with the membrane fastened and clamped form-closedly or positively between the two housing portions. One housing portion in this arrangement preferably is formed integrally with the filler connection while the other one is fastened thereat, for instance, by welding.
With the aid of such valves one obtains exact valve controls. The valves become responsive at extremely low pressures thus avoiding any overload of the tank in case of overpressure. As regards the design and fastening of the closure lid it will still be noted that when selecting an extremely great thread for the tank cover with a small depth of impression of the body the gripping trough for the lid may be fully recessed into the connection. This clearly reduces the danger of accidents.